Determining the size of your solar energy system starts with a simple question: how many solar panels do I need? As most people want to produce enough energy to completely eliminate their electricity bill, the first step is determining what size solar system will produce enough power to meet your household consumption levels. Ultimately, you will be calculating how many kilowatt hours of power you will need and finding the correct system size and number of solar panels to power your house.
How many solar panels do I need for my house?
If the average household consumes about 10,400 kWh per year and we assume 250-watt solar panels, we can use the high and low panel production ratios to calculate how many solar panels are needed on average. Thus, the typical homeowner will need 28 – 34 solar panels to cover 100% of energy usage (dependent on location and roof size).
How to calculate your own solar panel estimate
For those wondering how we estimated those numbers for energy consumption and required number of solar panels, here’s the breakdown. When you want to understand how much power you’ll need, start by looking at how many kilowatt hours (kWh) of electricity you use in a year. Most utilities provide you with your total power consumption for the last twelve months on your monthly bill. To offer some perspective, one kWh is 1,000 watts of power being used in an hour. So, if you have 20 lights in your home and they all use 50-watt bulbs, having every light on in your house for one hour would use up one kWh of electricity. According to the latest data from the U.S Energy Information Administration, in 2016 the average American household used 897 kWh per month. Said differently, the average American household consumes just under 11,000 kWh per year.
In order to find a range for number of solar panels, we compared Arizona and Maine’s solar panel production ratios, 1.31 and 1.61, the highest and lowest in the U.S. We then took 11,000 kWh and divided it by the respective ratios and then divided that number by 250 (the typical panel wattage). That calculation gave us high and lows for the average number of panels a homeowner will need.
How many kWh can your solar panels produce?
The amount of power (kWh) your solar energy system can produce depends on how much sunlight exposure your roof receives. The amount of sunlight you get in a year depends on both where you are in the country, and what time of year it is. California has more sunny days annually than New England. But in either location, you’ll be able to produce enough power to cover your energy needs! If you live in an area that gets less sun, you’ll just need to have a larger system installed at your home.
Two comparably sized households in California and Massachusetts consume the average amount of electricity for an American household, about 10,400 kWh annually. The California household needs a 7.0 kW system to cover 100% of their energy needs. By comparison, the comparable household in Massachusetts needs an 8.8 kW system to cover their energy needs. Solar panel systems in California are smaller than the solar panel systems in Massachusetts but are able to produce the same amount of power because they’re exposed to more sunlight each year. Homeowners in less sunny areas, like Massachusetts, can make up for this disparity by simply using more efficient panels or increasing the size of their solar energy system, resulting in slightly more solar panels on their rooftop!
In order to offer comparison data on how many panels and how much power you will need, we’ve compiled a table that compares average annual energy need to estimate the number of panels required to offset typical energy demand. We looked at data for the 6 most common system sizes that we see active in the EnergySage Solar Marketplace. In order to calculate the below data, we averaged annual kWh production in the top 12 solar states and assumed standard 250-watt panels in order to calculate how many panels you would need. The average system size in the U.S. is 5kW (5000 watts) so you can use that as a benchmark if you’re unclear on what your power needs will be.
Check out our video summarizing the key points to remember when deciding how many solar panels you need:
How many solar panels do I need? System size comparison
|System size (kW)||Average annual production (kWh)||Estimated number of solar panels|
The table above assumes that you’re using standard efficiency panel. However, the number of panels you need to power your home, and the amount of space that your system will take up on your roof, will change if you’re using lower-efficiency panels or high-efficiency panels. Below is a table that will give you a sense of how much space your system will take up on your roof, depending on how efficient the solar panels you select are.
How many solar panels can I fit on my roof? System size compared to square footage
|System size (kW)||Low efficiency panels (sq. feet)||Medium efficiency panels (sq. feet)||High efficiency panels (sq. feet)|
Perhaps one of the most difficult aspects of sizing a solar panel system is estimating annual energy usage for your household. A number of larger consumer products or add-ons can significantly change your annual kilowatt-hour requirements and thus can greatly impact how many panels you will need. For example, if you’ll be running central air conditioning or powering a heated swimming pool in your backyard, the size of your solar panel array could be drastically altered. To get a feel for the energy impact of various products you may have or may be considering for your home, check out this table comparison:
How many solar panels do I need for common household products?
|Product||Average Annual KWH Required||Estimate number of solar panels needed|
|Air Conditioning Unit||215||<1|
|Central Air Conditioning||1,000||3|
|Heated Swimming Pool||2,500||8|
|Hot Tub (outdoor)||3,300||11|
From reviewing the various kWh requirements for everyday household appliances and products, one thing is clear: certain add-ons will dynamically change monthly energy use and solar panel system size. For example, pairing your electric vehicle with solar panels is a great way to reduce carbon emissions and improve energy efficiency, however, it should be planned accordingly considering it could potentially double the size of your PV system. Though it is certainly possible to install a solar system and then add more panels later on to accommodate increased energy needs, the most pragmatic option is to size your system as accurately as possible based on your expected purchases such as an electric vehicle, swimming pool or central air system. Asking yourself “how many solar panels will I need for my refrigerator, my hot tub” and etc is a great habit for any new solar homeowner.
Three Tips for Solar Shoppers
1. Homeowners who get multiple quotes save 10% or more
As with any big ticket purchase, shopping for a solar panel installation takes a lot of research and consideration, including a thorough review of the companies in your area. A recent report by the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) recommended that consumers compare as many solar options as possible to avoid paying inflated prices offered by the large installers in the solar industry.
To find the smaller contractors that typically offer lower prices, you’ll need to use an installer network like EnergySage. You can receive free quotes from vetted installers local to you when you register your property on our Solar Marketplace – homeowners who get 3 or more quotes can expect to save $5,000 to $10,000 on their solar panel installation.
2. The biggest installers typically don’t offer the best price
The bigger isn’t always better mantra is one of the main reasons we strongly encourage homeowners to consider all of their solar options, not just the brands large enough to pay for the most advertising. A recent report by the U.S. government found that large installers are $2,000 to $5,000 more expensive than small solar companies. If you have offers from some of the big installers in solar, make sure you compare those bids with quotes from local installers to ensure you don’t overpay for solar.
3. Comparing all your equipment options is just as important
National-scale installers don’t just offer higher prices – they also tend to have fewer solar equipment options, which can have a significant impact on your system’s electricity production. By collecting a diverse array of solar bids, you can compare costs and savings based on the different equipment packages available to you.
There are multiple variables to consider when seeking out the best solar panels on the market. While certain panels will have higher efficiency ratings than others, investing in top-of-the-line solar equipment doesn’t always result in higher savings. The only way to find the “sweet spot” for your property is to evaluate quotes with varying equipment and financing offers.
For any homeowner in the early stage of shopping for solar that would just like a ballpark estimate for an installation, try our Solar Calculator that offers upfront cost and long-term savings estimates based on your location and roof type. For those looking to get quotes from local contractors today, check out our quote comparison platform.